Magnets zap migraines

Migraine sufferers might soon be able to block an imminent attack using a device that targets the brain with a powerful magnetic field.

The technique, called transcranial magnetic stimulation (TMS), triggers activity in the brain's nerve cells and is already being tested as a way to treat depression. Two small clinical trials have now shown that delivering TMS to the brain in the early stages of a migraine seems to halt it in its tracks.

Migraines are crippling headaches that affect around 10% of people in the United States. They are sometime preceded by an 'aura', in which a person sees flashing or shimmering light, blind spots or feels tingling.

Yousef Mohammad at Ohio State University Medical Center, Columbus, and his colleagues asked 43 patients to come to the hospital's emergency room when they experienced an aura. Half of them received two short blasts of TMS to the back of the head and half received a placebo blast.

After two hours, nearly 70% of the patients who received the TMS reported that they had a mild headache or none at all, compared with 48% of those who received the placebo. Most studies of migraine, like this one, tend to show a very strong placebo effect from a dummy treatment. Mohammad reports his results at the American Headache Society (AHS) meeting in Los Angeles today.

Adrian Upton, a neurologist at McMaster University in Ontario, Canada, reported similar results from a 42-strong trial at a meeting earlier this year. In addition, he found that patients reported greater improvement after two or three TMS treatments. "That's the biggest puzzle — we have no idea why," he says.

Portable relief

“The critical question is what is TMS actually doing in the brain.”

Michael Moskowitz,Massachusetts General Hospital, Charlestown

NeuraLieve, a company based in Sunnyvale, California has now built a portable TMS device the size of a large hairdryer that people could use out and about. The company, which is working with Mohammad and Upton, is supporting a larger clinical trial of the device in 160 patients across the United States. The aim is to gain enough data to get the device approved by the US Food and Drug Administration, says company president Gary Stroy.

A portable TMS would cost between $1,000 and $2,000, and patients would also pay $15-25 for each treatment using a chip-programmed card. Mohammad reported some preliminary data at the AHS meeting suggesting that this device is effective.

Mohammad and colleague's results back the idea that the aura of a migraine is caused by a slow-spreading region of intensely excited neurons in the brain's cortex, which then become exhausted. The highly active neurons are thought to trigger a cascade of events that activate pain sensors in the brain, partly by causing the expansion of blood vessels.

The magnetic fields created by TMS suppress the activity of the neurons and seem to prevent the excitation spreading, so that the aura is halted, aborting the imminent headache.

The pill approach

Migraines are currently treated with drugs called triptans that narrow blood vessels, but some patients do not respond and there is a risk of side effects such as heart attacks.

It is unclear whether TMS would also help to relieve everyday headaches, but Stroy says that he hopes to test that next.

Ultimately, researchers want to improve their understanding of the precise sequence of events during a migraine, says neuroscientist Michael Moskowitz, who studies the condition at Massachusetts General Hospital in Charlestown. "The critical question is what is TMS actually doing in the brain," he says. "I have seen a lot of these cures come and go and I'm always very sceptical."